The present invention is directed to saw chain grinding apparatus, and more particularly, to apparatus for grinding depth gauges in a saw chain.
A saw chain, as the term is used herein, refers to an endless chain composed of plural cutter links. Each link provides, on its outer, cutting surface, a depth gauge and a cutter blade spaced therefrom. In chain saw operation, the depth gauge leads the cutter blade, with contact between the depth gauge and the article being cut serving to space the chain from the article for optimal cutting by the soon-to-arrive cutter blade. The depth of cut, i.e., the height that the cutter blade should project above the depth gauge, varies typically between about twenty and fifty mils.
Some apparatus for grinding depth gauges in a saw chain are known in the prior art. Such apparatus operate to grind each depth gauge to a selected depth relative to the base portion of the associated cutter link, not relative to the cutter blade. An apparent disadvantage of this approach arises when the cutter blades of the chain links have become worn or chipped away to various degrees, i.e. where the depths of the various blades, with respect to base portions of associated cutter links, is variable. The depth differential between associated cutter blades and depth gauges are correspondingly variable. This impairs cutting efficiency.
A general object of the present invention is to provide apparatus for cutting depth gauges in a saw chain to a selected uniform depth with respect to associated cutter blades in the chain.
More particularly, it is an object of the invention to provide such apparatus wherein the depth of grinding of a depth gauge in a saw chain cutter link is limited by co-action between the associated cutter blade and the apparatus.
Still another object of the invention is to provide such apparatus which is operable to position one of a succession of cutter links in a saw chain at a preselected grinding position.
Still another object of the invention is to provide such apparatus which is adjustable to accommodate a wide variety of saw chain sizes.
The apparatus of the present invention includes a grinding wheel and a platform on which a selected saw chain cutter link is mounted for shifting therewith, toward and away from the wheel. A guide member mounted adjacent the wheel is positioned to contact the cutter blade in the selected link, to limit the closest approach between the wheel and the associated depth gauge. The depth gauge is ground to a selected depth relative to the associated cutter blade.
In a preferred embodiment of the invention, the platform is carried on a pivot arm for shifting therewith along a path substantially tangential to the contacted grinding portion of the wheel's grinding surface. A spring operatively connected to the arm urges the platform toward the grinding wheel, in a direction substantially normal to the just-mentioned tangential path. As the platform is shifted toward the grinding wheel, contact between the cutter blade in the selected cutter link and the guide member produces shifting of the platform in a direction opposite the urging of the spring, to limit the closest approach between the associated depth gauge and the grinding wheel.
Also disclosed herein is mechanism for positioning cutter links in a saw chain at selected positions on the platform.